This invention relates to a medical unit or device aimed at improving the conditions of the setting and holding of an implant in an anatomical duct, particularly in the case of a vascular implant or endoprosthesis for aneurysm that must be set at least partly by percutaneous endoluminal access.
Various types of implants and various techniques for setting them are already known.
For instance, the U.S. Pat. No. 5,527,355 or 5,707,378 show a device and a method for treating aneurysms through the fitting of a strap around the vessel outer surface, where spring-like means are used to hold the implant against the vessel (stents).
Is thus known a medical unit for the treatment of an affection of an anatomical duct, comprising:
an implant that can be introduced in the duct to be treated, the implant having a general axis and presenting, substantially along said axis, two free ends, respectively proximal and distal,
at least one lining, to at least partly line the outer duct wall, essentially opposite the proximal end of the implant,
and means for fastening the lining to the implant, through the duct wall, so as to hold internally the implant against the duct wall.
According to these patents, as many as two lining straps have been provided on both proximal and distal ends of the implant, which is itself designed so as to be introduced in a radially restrained state. Thereafter, it expands radially to treat the aneurysm.
Nonetheless, some problems remain, related to the conditions under which the strap is set around the given duct and the implant is fastened to this duct wall, as well as to the possible fluidtight conditions required vis-à-vis the circulating fluid.
It will be noted that, in the aforementioned patents, the method used to fasten each strap around the duct can cause a problem, especially if the aorta is concerned, since it can be particularly difficult to try to completely surround it.
Moreover, the physician may find it difficult to succeed in positioning the lining strap exactly across from the corresponding end of the implant, which nonetheless must be done to insure an adequate fastening between them. This fastening is indeed achieved by the hooks connected to one of the implant stents.
The way in which this invention solves the problem consists in particular in providing a medical unit that also includes means of setting the fastening elements, which are distinct from the implant, so as to preferably install these fastening means from the outside of the duct, toward the implant.
Hence the implant fastening hooks are not used to bind together the lining, the duct and the implant. Moreover, according to the invention, the implant could be devoid of any fastening hook to anchor it in the duct
Approaching the duct from the outside appears to be technically the least dangerous so far for the patient, all the more so if, as otherwise suggested, the fastening between lining strap(s) and implant is performed, through the duct, by means of surgical staples set in place by a surgical stapler designed to introduce and curve the free ends of each staple from only one side of the given duct An endoscopic (or laparoscopic) approach is proposed.
It is to be noted that these xe2x80x9cstaplers,xe2x80x9d including the endoscopic staplers (such as the one from ETHICON(copyright) in U.S. Pat. No. 5,470,010 or 5,333,772), have not been designed so far to staple through a duct where a fluid circulates (such as a blood vessel), because of possible leaks due to the perforation caused by the staple. It is thus an application that is uncommon to date and goes against the current instructions for the use of such an equipment
It should also be noted that the choice of both the stapler and the staple is of great significance. A cutaneous stapler (such as a stapler like ROYAL(copyright) from the firm AUTOSUTURE) seems unsuitable in that the staple is initially lying flat, until the stapler closes it progressively to a shape in xe2x80x9cxe2x80x9d by driving it forward and then closing in its free ends. What is a priori an effective way to draw together two lips of a cut does not seem appropriate to a fastening through an internal duct containing body fluids, a fragile vessel especially.
In this respect, an important characteristic of this invention consists in recommending that the staples be, when first introduced (hence before the stapler acts to distort them) in the shape of a xe2x80x9cxe2x80x9d so that they go through the lining, the duct and the implant. Then in a second step (after they go through the lining, the duct and the implant), the stapler will bring them substantially to the shape of a xe2x80x9cxe2x80x9d
More broadly, and even if fastening means other than staples are used, such as the rivets described in FR 97 16625, another important characteristic of the invention is the recommendation that these fastening means consist in means of tightening that have, parallel to their introduction axis (through the aforementioned layers), a difference in length between the initial stage of introduction through the outer lining, the duct and the implant, and a second fastening stage after this introduction, so as to tightly pinch the duct wall between the outer lining and the inner implant, thus insuring fluidtightness between the implant and the wall of said duct vis-à-vis the fluid that circulates in the duct.
The (each) lining can be in the form of a local pad placed in the same area as the fastening means or, even better, as a split strap or collar at the periphery of the duct.
To insure a xe2x80x9csoftxe2x80x9d yet uniform enough contact between the lining and the duct, the preferred lining will present a frame covered (at least on the inside) by a damping pad.
So as to better hold it in place at the time of its fastening and thereafter, the preferred lining will be mechanically resistant in the sense of its thickness, in such a way as to constitute a support for the fastening means.
And, to promote a lasting hold, the lining can include an xe2x80x9cadhesivexe2x80x9d layer (favorable to cellular development and designed to come in contact with the anatomical duct).
Since not all anatomical ducts have the same section and since a same duct can also display different sections for different persons, this invention also provides that, in the case of a strap (or open collar), the preferred lining will originally have a length superior to the duct circumference that can be trimmed later to be adjusted to the duct section.
An added characteristic of this invention provides that the lining be fit to be pierced, or be structurally designed, with openings (preferably self-obturating openings) to allow the fastening means to pass therethrough thus easing such a passage.
A further aspect of the invention relates to the way of implanting and using the medical unit aforedescribed (see the enclosed  less than  less than method claims greater than  greater than  14 to 17).